Valves for turbomachines, in particular steam turbines, are given special significance, since the feed of steam to a steam turbine has to have substantially two properties. These would be firstly regulating the steam which flows into the steam turbine and, in the case of a disruption of the quick-action closure of the valve, in order to interrupt the feed of steam. There are embodiments of valves, in which said two properties are arranged in a single valve housing. On account of the high temperatures and the high pressures of the steam, the technical requirements of valves of this type are particularly high. The opening and closing at high temperatures and high pressures prove difficult. As a rule, a valve cone has to be configured in valves such that it can be moved in one direction. The forces for being able to move said valve cone are comparatively high and are either of hydraulic or electrohydraulic configuration.
Furthermore, the valves have to be configured in such a way, for reasons of safety, that a fault or a failure of the actuation leads to automatic closure of the valves (“valve closed” safety position).